Robotics is a traditional research area which is rapidly expanding due to the ongoing exploitation of intelligent autonomous agents like self-driving cars and drones, industrial robots for production and humanoids for the elderly. The course focuses on the knowledge a robot needs to act in the environment and to understand what it can possibly do. It introduces and discusses the notions and relationships that are needed to “understand” a generic scenario and shows how to structure an ontology to organize such knowledge. In particular, it focuses on how to understand and model capacities, actions, contexts and environments. The flow of information between the knowledge module and the planning and scheduling modules in a generic artificial agent is presented.